The technologies of the present disclosure relate to an image display device for displaying images and an image display medium including the image display device.
A passport, which is an identity certification medium, includes a bearer display section displaying a face image of the bearer. When the face image is displayed by attaching a face photograph, the face image may be tampered by replacing the photograph. Thus, in recent years, a face image of the bearer has been formed on the sheet surface in the bearer display section instead of attaching a face photograph (see Japanese Laid-Open Patent Publication No. 2002-226740, Japanese Laid-Open Patent Publication No. 49-131142 and Japanese Laid-Open Patent Publication No. 2006-123174, for example). Further, optical variable device (OVD) technologies have been used effectively to limit fraud (see Japanese Laid-Open Patent Publication No. 10-49647, for example). Examples of the OVD technologies include an optical film that has a diffraction grating and is adhered onto a face image, and a face image generated by a hologram by thermally transferring a section of a hologram ribbon to a passport.
However, passports incorporating such OVD technologies are still susceptible to counterfeit, tampering or other frauds. Thus, technologies have been sought that allow easy verification of the authenticity of face images through visual check by a user. Easy verification of image authenticity is required not only for bearer display sections of passports but also for other image display devices that display images using OVD technologies.